The text next to this graph is revealing as to why the Hockey Stick is used exclusively when discussing "greenhouse warming":

By overlying the reconstructed temperature record of the past millennium with atmospheric CO2 from the Law Dome Ice Core the relationship between the two is apparent. More sophisticated analyses, such as that by Crowley et al, shows much of the temperature record can be explained by changes in solar activity, volcanic activity, and greenhouse gases (although the recent warming cannot be explained without taking into account changes in greenhouse gases). A similar analysis, with similar conclusions, is provided by Mann et al. The gradual downward trend that has been observed over the past 1000 years may also have a human component – recent research from the Livermore National Laboratory suggests that deforestation may have reduced the amount of the sun’s warmth absorbed at ground level.

Of course, if Crowley had managed to keep his data somewhere safe (like in a tin box under his bed) we might be able to check that "sophisticated analysis" for ourselves, wouldn’t we?

24 Comments

So, the ad hom is that Crowley is incompetent is it, John? And a figure of fun to boot?

John replies: No, not really. Crowley may be a competent scientist but we’ll never know for sure if he can’t put his scientific data in a safe place where people can look at it later. On the other hand to actually say “I don’t know where I put my original data” must be the geoscientific version of “the dog ate my homework”. Clearly these excuses must impress you, Peter, but not the rest of us.

Peter,
there is insufficient evidence to call Crowley’s actions incompetent. Amateurish, immature, deceptive and careless are all equally valid conclusions. This makes him a figure of pity, not fun. For the rest of us it is a time of sadness at the loss of some real science. Without the data we will never know if he is right or wrong. With out the data, it is just the opinion of a careless person instead of a valid contribution to science from a competent scientist. Too bad.

Peter, in comment section of http://www.climateaudit.org/index.php?p=103 I posted a question to you on a subject that you do claim to be knowlegable about, growing things. Why have you not answered the question? Are you really not a farmer?

What I am looking for is the temperature data from the Law Dome ice core. That would give another proxy on it’s own. That combination was once on a graph, which showed that CO2 levels were following temperatures in the pre-industrial era with some 50 years delay. But while the CO2 data can be downloaded from the NOAA web site, the temperature data are not on line anywhere…

John writes: You could just ask the authors of the study for the data. Let me know if they reply in words of more than one syllable.

Apart from bore hole temperatures, there are no temperature data in ice cores. Only a variety of isotope proxies (dD, d18O) in the ice which are used to reconstruct (SST) temperature of the source during evaporation(deuterium excess) and temperature during sublimation of the snow. Those processes have a high supposition value and may be completely frustrated by other variables -unaccounted for-. Most notably, the rate of precipitation, changes in isotope ratios in the source for instance by changes in prevailing wind directions.

Peter, you keep missing the point. We are not interested in opinions or beliefs. Whether I believe you are a farmer or not is irrelevant. On the assumption you really are a farmer, you were asked a question that a knowlegeable farmer should be able to answer, at least in general terms. Instead of a rational answer to the question you blather on about beliefs.

This could be interpreted in several ways; You are a farmer and you know the answer and it hurts the position you have taken on anthropogenic global warming OR, you don’t know the answer because you do not have any real knowlege of farming. With good advisors and mentors, a simpleton can be a successful farmer. They just won’t understand why they have to do certain things or why things happen as long as they are physically able to do what they are told.

So, do we get a useful answer to a reasonable question of facts or do we get more blather about beliefs and opinions?

Actually you wondered “Perhaps “Peter the farmer” can shed some useful comments on this.” See, no question mark! And at the time I couldn’t. But you did ASK above “Are you really not a farmer?” to which I replied, Still here’s a reply to your musings.

OK, you list four variables “Tree growth responds strongly to 4 things that can vary from year to year, water, CO2, sunlight and temperature”. Implicit in this is that trees DO respond strongly to temperature. OK, well, what the experts (remember, I’m not one) do I think is find places where the other three variable you list (and others I guess) aren’t limiting and them see if there is a temperature signal. Sounds like a worthwhile exercise to me, there is something to be learn’t from tree rings despite the best efforts of some here to rubbish them. Now, do they then use JUST tree ring data. Nope.

Was your yield higher or lower than average in 2003? In other words: do you think that the u-shape response (poor growth at cold and hot conditions, optimum growth at average conditions) is a sensible approach, given your own experience as a farmer?

It is an oversimplification to say that dendrochronology is ring counting based on rainfall and the physiology of trees. Many other factors are considered. This is especially true with the old bristlecones, as their growth can be affected by slope gradient, sun, wind, soil properties, temperature and snow accumulation. The more a tree’s rate of growth has been limited by such environmental factors, the more variation in ring to ring growth will be present. This variation is referred to as sensitivity and the lack of ring variability is called complacency. Trees showing sensitive rings are those affected by conditions like slope gradient, poor soils, little moisture. Those showing complacent rings have generally constant climatic conditions such as a high water table, good soil, or protected locations.

As an organic gardener in my free time, I know one of the basic principles in organic gardening is “mulching”, the covering of soil around the plants of interest with cut grass or other organics. Besides other benefits (temperature, moisture and weed control), the CO2 which emerges from the decay of the mulch increases the growth of the plants…

Several experiments have shown the increase of tree growth by CO2, depending of other constraints. That may be species dependent, temperature/climate dependent, moisture dependent, and nutritients dependent.

Thus in general, one can wonder if tree rings are good proxies for past and current temperatures at all…

Thank you Ferdinand for providing an expert opinion on factors that affect the growing of plants. It is apparent from many posts that “Peter the farmer” is only capable of professing blind faith in the “trained climatologists”. Their ability to see temperature signals in things that grow no matter how much noise there is from other factors is simply miraculous. He certainly doesn’t mention what kind of independent indicators of water and sunlight are used to account for their effects.

Honest answer: We used to grow a little barley (still too wet, and perhaps to cold, up here for wheat), infact we have grown it for fourty years continously (and, yes, we’ve not got the records anymore – sinsiter?). I think I remember yeild in 2003 was in the ‘OK’ if down somewhat area – it wasn’t searingly hot here, we had some rain bit not quite enough, the crop ripened early. Barley doesn’t like it too hot, it doesn’t like it too cold. Likewise, if it’s too wet or too dry it sufferers. It has a ideal climate envelope range it likes (like many species…).

I suspect you could glean some idea of the weather of an individual year from our yields or, for instance, from straw colour – broadly the less golden it is the wetter and more delayed harvest time was but other proxy data would be needed to give a fuller picture. Unfortunately again I’ve not collated and placed on the web any records we had (I’m holding data back again ;)). But, I’m not sure anyone uses barley yeilds to reconstruct past temperatures :)? Besides, yet more factors, like acidity (which drops rapidly up here unless the ground is regularily limed), or variety, or weed control, perhaps even if the ground is ploughed early or late, or if machinery breaks down will effect yeilds.

So, I do think arable crops do best when conditions, climate and others, are optimum for them. They thus can give an indication of climate. But their use as reliable proxy indicators of temperature must be problematic. However, if everything else bar climate was optimum and equal I think it must be the case the climate signal would be clearer if still, I guess, not reliable.

What does this say about the use of tree rings? Not much? That when compiling proxy records you shouldn’t rely on just one indicator? Of course, who does? That gleaning useful data from proxys is difficult? Of course, who claims otherwise? That carefully selected tree ring data tells us nothing about climate. No. That we can eliminate proxy reconstruction by author we don’t like? Nope.

Ferdinand, I’m doubtful that in the open any CO2 from mulches can have a meaningful effect on CO2 levels except, perhaps, very close to the ground. Surely a mulches effect on crops is much more likely due to enhanced fertily, and better soil structure and moisture retention? But, I’m listening.

Fame at last… You’re right, that fig is way out of date. I’ve done a temporary fix and will hopefully get around to a better one. The accompanying text and conclusions still hold, though. In fact, they’re somewhat strengthened because the alternative reconstructions provide a better fit to the forcing data and model results (e.g. Rind 04, Zoritz 04, Hegerl 03, Waple 02 etc).

John writes: George Orwell was right. It is indeed possible to alter the present by rewriting the past. How nice that you put a spaghetti diagram of different studies in front of the Mann Hockey Stick in order to obscure it. You might not have noticed, but Mann (and mouthpiece David Appell) specifically deny that the Medieval Warm Period and the Little Ice Age were global climatic events. See my post Sci-Am: Mann and the Hockey Stick. So why the Mann Hockey Stick (obscured) is on a diagram marked with the MWP and LIA is beyond me.

In point of fact, if the accompanying text and conclusions still hold, please present any empirical evidence that rising carbon dioxide in the atmosphere causes rising temperatures. Note that I said empirical and not modelled.

The influence of CO2 from mulching obviously is for smaller plants, and specifically for plants where leaf forming is of importance (like salad, parsley, celery,…). The microclimate is important too: reduce wind speeds by planting hedges. I have done several experiments and it works…
For trees, the increasing CO2 levels probably play a role, if there are no other constraints. In many cases the lack of fertilisers may play a role too on poor soils. Together with more CO2, more nitrogen oxydes are emitted (and more ammonia from agriculture), which may give a boost in growth…

For the high North trees, the most important constraint probably is temperature (and humidity) in the growing season. The more intruiging it is that especially these type of tree series don’t show a post-1950/1980 warming. See e.g. the over 7,000 year series of North Finland at page 14/15 of Pages: No MWP, no LIA and a cooling after 1950…

Wind speeds will affect the open field CO2 experiments most, as more wind will dilute the CO2 levels (that is the reason for planting hedges too!). That is less so for open top experiments, as CO2 is heavier than air and will be diluted only at higher wind speeds. And closed top experiments are of course not affected by wind.
On the other side, open field experiments are more natural for other constraints like rain, humidity of leafs and soils,…

Actually “grain” yields was one of the proxies Ruediger Glaser used in his book “Climate History of Central Europe”, published 2001.
He tried to “describe” the “weather” in Central Europe during the last 1.000 years using town chronicles, weather diaries, tree rings, grain and wine production, harvesting time, floodings…

He concluded that in the MWO we had “hot” summers and “cold” winters, with the “hot” summers primarily responsible for the overall “warm” climate.
While today we have generally “mild” summers and “mild” winters, with the “mild” winters adding a lot more to the average “warm” temperature.
With all in all roughly the same “average” temperature as during the MWO right now.
Although he cautions that this doesn´t mean that the issue of global warming should be dismissed.
(I should add that his data sets probably ended somewhere in the 1990s.)

Concerning tree rings.
He worked with the “Hohenheim Dendro research center” in Germany.
Quote from the book (my translation):“Tree rings from “moderate” locations, which are typical for Central Europe except for the Alpes and some other hilly regions (Harz mountains, Black Forest region etc. in Germany) aren´t conclusive in “average” years. Because they don´t show a uniform growth of tree rings in those years. Only in years with extreme climate conditions is the tree ring growth “uniform” even in moderate locations. These “signatures” are called “Weiserintervalle” or “Weiserjahre”. Accordingly only these signatures were used in his research.”

Probably meaning that in “average” years other influences (location, soil, precipitation, human and animal actions, …) tend to “over-shadow” the temperature factor.

Well I never! As I said “I suspect you could glean some idea of the weather of an individual year from our yields”, looks like someone tried something similar.

As to trees ring. Not sure anyone is trying to make out they are more than one of several available proxies? I also readily accept the MWP and LIA across Europe. I just doubt (i.e. I’m not certain – yeah, I know that heresy to some) they were global.